1. Field of the Invention
This invention relates to footwear with an air cushion and a method for making the same.
2. Description of the Related Art
FIGS. 1 and 2 illustrate a conventional shoe disclosed in U.S. Pat. No. 4,722,131. The shoe includes an upper 8, an outsole 9, and an air cushion 7 sandwiched between the upper 8 and the outsole 9. The air cushion 7 is made from an elastomeric material so as to be inflatable up to about 40 psi, and is formed with a plurality of depressions 70 for the purpose of providing vertical support thereto. Since the air cushion 7 is made from an elastomeric material, it is relatively soft. As a consequence, the strength of the vertical support given by the depressions 70 to the air cushion 7 is insufficient. A foam material can be used to encapsulate the air cushion 2 and fill the depressions 70 so as to enhance the strength of the vertical support to the air cushion 7. However, the foam material is also a soft material. As such, there is still a need to enhance the strength of the vertical support to a conventional air cushion. Moreover, using a foam material to enhance the strength of the vertical support to the air cushion significantly increases the manufacturing cost of the shoe. The depressions 70 divide the air cushion 7 into a plurality of cells that are in fluid communication with one other. However, the structure as such is disadvantageous in that once the air cushion 70 is compressed at one end thereof, the other end of the air cushion 70 expands, so that said one end of the air cushion 70 will be significantly depressed, which results in an imbalance in the cushioning effect between the two ends of the air cushion 70 and insufficient cushioning at said one end of the air cushion 70.